add Confidential Computing readiness check + collect nvidia-smi conf-compute -q

New read-only "Check" step reports whether this server can run NVIDIA
Confidential Computing: CPU TEE support (Intel TDX / AMD SEV-SNP, via
dmesg and kvm_amd sysfs params) and GPU firmware CC capability (via
`nvidia-smi conf-compute -q`). Also collect that command's output into
the techdump export bundle.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

audit/internal/webui/api.go

@@ -135,7 +135,7 @@ func defaultTaskPriority(target string, params taskParams) int {
 		return taskPriorityBurn
 	case "nvidia", "nvidia-targeted-stress", "nvidia-targeted-power", "nvidia-pulse",
 		"nvidia-interconnect", "nvidia-bandwidth", "memory", "storage", "cpu",
-		"amd", "amd-mem", "amd-bandwidth":
+		"amd", "amd-mem", "amd-bandwidth", "confidential-computing":
 		if params.StressMode {
 			return taskPriorityValidateStress
 		}